Recoilless firearm and cartridge therefor

ABSTRACT

A recoilless firearm, and round of ammunition therefore, are disclosed. The firearm has a bolt having a bore therein for the passage of exhaust gasses from the firing chamber to an exhaust tube at the rear end of the weapon. The exhaust tube contains a restricted opening, such as a venturi, to counter recoil. The round of ammunition has a single gas discharge opening in its rear end, with the ammunition casing having no apertures in the walls thereof. The use of the recoilless firearm, and round of ammunition therefor, of the present invention allows automatic and semiautomatic weapons to be extremely light while utilizing powerful ammunition propelling charges.

United States Patent Febres RECOILLESS FIREARM AND CARTRIDGE THEREFOR [76] Inventor: Vasco Altuve Febres, Edificio E1 Convento, 78, Avenida Principal de Santa Sofia, Caracas, Venezuela 22 Filed: Nov. 16, 1910 21 Appl. No.: 89,660

8/1967 Kruzell 89/187 X zza 2/2 2/4 245 224 11 3,738,219 1 June 12, 1973 Primary Examiner-Samuel W. Engle AttorneyCushman, Darby & Cushman [57] ABSTRACT A recoilless firearm, and round of ammunition therefore, are disclosed. The firearm has a bolt having a bore therein for the passage of exhaust gasses from the firing chamber to an exhaust tube at the rear end of the weapon. The exhaust tube contains a restricted opening, such as a venturi, to counter recoil. The round of ammunition has a single gas discharge opening in its rear end, with the ammunition casing having no apertures in the walls thereof. The use of the recoilless firearm, and round of ammunition therefor, of the present invention allows automatic and semiautomatic weap ons to be extremely light while powerful ammunition propelling charges.

9 Claims, 31 Drawing Figures INVENTOR PATENI'EB m! 2 W5 sum m M m? $3 B b r/// 7/// W\\ 3% SQ vb v 3 NQ suazmuw INVENTOR PATENIED JUN 1 2197s QNN \ Hg ywzw m /i L 5 ATTORNEYS PATENTED JUM MUM N W QM w QR m wk WNW INVENTOR E4560 z44 70V 725 455 BY MAM Ju/ My ATTORNEYS PATENIEflJun I 21913 SHEET 8 0F 8 R S m mm m M mmh w F: Qmwv vmh m M Q umb mmh m q 0 wwl g g m fi 0 Q mun, A mwln NW! w fi $1M. *Q m lnh who V @v m E U mU n A U nU vs i Who 9m v ATTORNEYS RECOILLESS FIREARM AND CARTRIDGE THEREFOR BACKGROUND OF THE INVENTION Recoilless firearms are well known to the art, and generally operate on the known principle of passing a certain portion of propellant gasses rearward after firing to counteract the recoil. Generally, these gasses are passed through a venturi or other type of opening in the rear portion of the firearm. Such weapons are described by numerous publications, such as Cooke, U. S. Pat. No. 1,380,358, issued June 7, 1921; Hughes, British Pat. No. 468,583, issued July 8, 1937; Eksergian, U. S. Pat. No. 2,405,414, issued Aug. 6, 1946; Kroeger et al., U. S. Pat. No. 2,466,714, issued Apr. 12, 1949; Burney, U.S. Pat. No. 2,489,747, issued Nov. 29, 1949; Burney, U. S. Pat. No. 2,489,748, issued Nov. 29, 1949; Barker, U. S. Pat. No. 2,515,180, issued July 18, 1950; Musser, U. S. Pat. No. 2,696,760, issued Dec. 14, 1954; Musser, U. S. Pat. No. 2,924,149, issued Feb. 9, 1960; Abramson, U. S. Pat. No. 2,925,014, issued Feb. 16, 1960; Musser, U. S. Pat. No. 3,026,775, issued Mar. 27, 1962; Bender'sky, U. S. Pat. No. 3,118,376, issued Jan. 21, 1964; Blacker, U. S. Pat. No. 3,128,670, issued Apr. 14, 1964 and Bergman et al., U. S. Pat. No. 3,380,340, issued Apr. 30, 1968.

Most of the above patents (See: e.g. Bergman et al., Bendersky, Musser 149, Musser '775, Abramson, Kroeger et al., and Musser '760) utilize weapons wherein the ammunition propelling gasses are discharged through perforations in an inner casing and thereafter are passed rearward of the weapon. Blacker discloses the discharge of small shot or pellets out of an angled rear tube to counter recoil caused by discharge of a solid projectile. The Hughes British patent discloses a series of perforations in the end of the cartridge case aligning with a corresponding series of openings in the gun breach block to discharge a limited portion of gasses through the cartridge case base. The gun breech block openings are tapered in accordance with Pascals Law.

None of the above recoilless weapons utilize an axially reciprocating bolt or an axially reciprocating piston within such bolt. Most of the prior art practice has involved recoilless firearms wherein the firing chamber is considerably larger than the ammunition case diameter to provide adequate space for passage rearwards of gasses escaping from the multiple perforations in the cartridge body case walls. None of the above prior patents discloses a separable round of ammunition having a single axial opening in the rear end of the casing.

SUMMARY OF THE INVENTION The round of ammunition of the present invention has a single gas discharge opening in the center of the cartridge case base. The cartridge case itself is nonapertured, e.g. contains no perforations in the walls thereof. The projectile may have a stabilizing boom fixedly attached thereto, or such boom may be separably attached thereto. Alternatively, the projectile may be the type normally used in rifled barrelled weapons. The cartridge preferably has a gas check located within the gas discharge opening for sealing the space between the cartridge base and-a bolt or breech face of the weapon.

The recoilless weapon itself has a hollow bolt or moving breech mechanism, with a bore in the bolt generally aligned with the gas discharge opening in the cartridge. The firing chamber is generally of a size only slightly larger than the cartridge, as the cartridge case is nonapertured and there is no necessity to provide space for rearward discharge of gasses passing around the cartridge. The barrel of the weapon is conventional.

The bolts may be of the positive locked type, the hesitation locked type or the unlocked or blow-back type. In all three bolt variations, the weapon may be designed to fire from a closed bolt position or from an open bolt position.

The bolt preferably has a piston within the bolt bore, with the piston having an axial piston bore. The direct action of the gasses escaping rearward through the car tridge case base, cause the piston within the bore to move rearward, cock itself, unlock the bolt, move the bolt rearward, extract and eject the spent cartridge cases, and compress recoil springs of both bolt and piston. The firing cycle is completed by the action of the recoil springs impelling the bolt and the piston forward, with the forward motion of the bolt loading a new round of ammunition in the firing chamber. The bolt or the piston carries a primer striker on the front face thereof, and strikes and fires the primer at the forward extent of axial travel.

DESCRIPTION OF THE INVENTION The principle of the present invention differs radically from the operation of prior art recoilless weapons as described previously. In the present invention, a portion of the exhaust gasses are permitted to escape rearwards through a single opening in the center of the cartridge case base. After escaping from the opening provided in the base of the cartridge, the gasses pass into the bore of a hollow one-piece bolt or moving breech mechanism, pushing rearwards a cylindrical piston which is located in the bolt bore. The piston is also hollow and the exhaust gasses enter the piston, generally after the piston has travelled rearward a predetermined distance, and flow through the piston bore to an exhaust tube. The exhaust tube is fixed to the rear end of the receiver and the gasses exit from the exhaust tube through a venturi or similar opening or openings into the surrounding atmosphere, transmitting to the receiver a counterforce to neutralize the recoil.

The recoilless weapon barrel, which may be smooth or rifled, is manufactured by normal manufacturing techniques and affixed to the receiver by normal means. The barrel has a firing chamber similar to the conventional hunting rifle in that no provision need be made for the rearward passage of gasses escaping from multiple perforations on the cartridge case body walls. Thus, the firing chamber will generally be of only slightly larger diameter than the cartridge case.

The bolts utilized in this invention are generally hollow, one-piece bolts, which move or reciprocate axially within the receiver. These bolts may be positively locked during firing, by locking lugs in the bolt face engaging in corresponding recesses in the rear end of the barrel or in a barrel rearward extension, due to axial rotation of the bolt body. The bolt may also be hesitati'on-locked by rollers sliding out of the bolt body and engaging corresponding locking recesses in the receiver or in a barrel extension. Furthermore, the bolt may be of the unlocked, or blow-back", type with the bolt held forwards during firing by means of a bolt recoil spring. The recoilless weapon may be fired from a closed bolt position or from an open bolt position, irregardless of whether the bolt is of the locked, hesitation-locked, or blow-back type.

The positive locking of bolts and the hesitation looking of bolts are known in firearms design. However, the present invention utilizes a different method than known to the art to cause the bolt to axially rotate to lock itself or to cause the hesitation-locking rollers to slide outwardly from the bolt, or to make the blowback bolt reciprocate axially within the receiver. It is the direct action of the gasses produced in the cartridge escaping rearwards through the single opening in the case base into the bore of the hollow bolt or breech which causes the piston within the bolt to move rearwards, to cock itself, unlock the bolt, move the bolt rearward within the receiver, extract and eject the spent cartridge cases in conventional manner, and compress both bolt and piston recoil springs. After completing the rearward cycle, the bolt and piston are impelled forward by action of their respective recoil springs to continue ro complete the firing cycle. In the locked-bolt variation, the direct gas action upon the piston causes the piston to move rearward, unlocking the bolt, and the subsequent action of the piston recoil spring, moving the piston forward, locks the bolt for the next firing of the weapon.

As mentioned, the various types of bolts may include an axially reciprocating piston in the bores thereof. This piston also contains an axial bore, which is in communication, during at least a portion of the travel of the piston within the bolt bore, with the bolt bore. The front part of the piston is a primer striker which actually crushes the priming disk or primer in the cartridge. The piston moves rearward inside of the bolt bore by direct action of gasses passing through the cartridge case base gas discharge opening into the bolt bore. The rearward movement of the piston causes the bore to unlock and may cause the bolt to initiate its rearward movement (generally in cases wherein a cartridge is used which has an extremely large rear gas escape opening, providing little or no backward thrust on the bolt face after firing). The bolt unlocking is accomplished by a locking stud or similar device attached to the piston.

After firing the gasses flow through the bore of the bolt into the bore of the piston. This piston,'or at least a small portion of the rear portion thereof, is inserted into the bore of the exhaust tube, which directs the gasses to their final exit from the firearm. The other cycle of the movement of the piston within the bolt bore, e.g. the movement of the piston towards the front of the weapon, is accomplished by a recoil spring which generally is wound around a portion of the piston and rests on the frontal face of the exhaust tube. The piston recoil spring is independent from the bolt recoil spring described in detail hereinafter.

The receiver of the weapon is generally of tubular form, having a profile or various shapes, such as square or round and the receiver is generally open at both ends. The barrel will normally be inserted in the front end of the receiver and affixed to it by conventional methods, such as screws, pins, barrel screw cap or the like. The exhaust tube is affixed to the rear end of the receiver, generally in a removable manner. This exhaust tube, as mentioned previously, has a venturi or other opening or openings so that the gasses escaping from the opening in the cartridge case base, directed through the bore of the bolt and then through the bore of the piston and then entering the exhaust tube, will make their final exit into the surrounding atmosphere behind the shooter or operator of the weapon. As the exhaust tube is rigidly fixed to the receiver of the weapon, the gasses making their final exit through the venturi or other openings react upon the rear surfaces of the exhaust tube, transmitting to the receiver a counteracting force sufficient to neutralize the recoil produced by the firing of the weapon. The barrel is preferably inserted through the front opening in the receiver, and can also be inserted from the rear end of the receiver, or even inserted sideways from the middle front portion of the receiver. When the recoilless weapon of the present invention is a hand-held weapon, it will generally have a curved heavy sheet metal shoulder support affixed, permanently or removably, to the bottom rear portion of the receiver. The receiver will have the normal longitudinal openings or slots and/or perforations to permit the insertion of a cocking stud, locking stud, cartridge box magazine, trigger mechanism housings, which may be either inserted or affixed thereto, and perhaps means to permit or facilitate barrel cooling in the front part of the receiver or lateral introduction of the barrel into the receiver. Generally the receiver has conventional sighting apparatus, such as a complete telescopic sight or a rear metallic sight, attached to it.

Automatic functioning of the weapon is obtained by the use of the axially reciprocating bolts of the type described herein. These bolts function by the direct action of the gasses which pass rearward through the axial opening in the cartridge case base into the bore of the bolt and directly actuate either the bolt (in the blowback open bolt design) or the axially reciprocating piston within the bolt. 1n the locked bolt design, automatic fire is obtained by cocking the piston by means ofa sear located within the back bottom portion of the bolt body when the piston is violently moved backwards within the bolt bore, by the direct action of the aforesaid gasses to the cocking position. The piston cocking sear is actuated by a trigger lever in the trigger mechanism housing so that the sear releases the piston. When so released, the piston, under pressure from its own recoil spring, moves forward, whereupon a striker carried on the frontal section of the piston crushes a primer to fire the next cartridge. When the firing mechanism is activated to automatic firing, such as by means of a transverse selector with an uneven cut surface, a vertical and independently moving sear depressing arm, located within the trigger mechanism, moves upward to engage and depress the piston sear, which may be located in the bolt body, when the trigger is depressed (such trigger being generally swivelled on a frontal transverse pin on the trigger transverse housing). In such bolts as just described, wherein pistons are located inside the bolt bores, the sear may or may not protrude from the bolt. Generally, there will be a longitudinal recess on the underside of the bolt, so that the protruding sear actuating arm of the trigger, which arm in automatic firing position emerges from a convenient opening in the underside of the receiver, can stay in the protruded position as long as the trigger is depressed, with the bolt travelling over the arm without touching same when the bolt travels rearward upon firing. This sear actuating arm, in the up position, will depress the piston sear only when the bolt has reached its maximum forward or locked position.

In weapons utilizing a simple open bolt of the blowback design mentioned above, the bolt will have a normal recess in its underside so that a convenient, conventional sear will release the bolt, as in current machine pistol or submachine gun practice. When a blowback or unlocked bolt is used, but with a piston inside the bolt bore, the procedure for obtaining automatic fire is the same as described above for the locked bolt variation.

The cartridges of the present invention, which are used in the recoilless firearms of the present invention, generally comprise a projectile, a metal cartridge case, a projectile propelling charge, a priming device, and preferably a gas check piece. The projectile may be of the current types usedin small arms cartridges. The projectile may be a conventional large caliber projectile, having one or more rotating bands, with the projectile base separably attached to a projectile support, and a perforated boom with fins or guides attached to the projectile support. The projectile support may conveniently be a metal cup made of two or more portions which are simply joined together over recesses in the projectile and the perforated boom. This separable unit of projectile, projectile support, and boom, will become separated by rotation of the projectile after the unit leaves the muzzle of the recoilless weapon. Such an arrangement permits the use of an open cartridge case with large caliber projectiles and large propelling charges that require strong initial priming. In such situations, a priming charge will generally be located inside the hollow, perforated boom. The propelling charge will generally be located in the annular space between the boom and the cartridge case. When the priming charge is ignited, it will generally flare out of the booms body perforations into the case to ignite the main propelling charge. The guides on the boom body function to stabilize the projectile inside of the barrel of the recoilless weapon. A conventional primer is conveniently attached to the rear end of the boom and serves to ignite the priming charge inside the boom body. The projectile support will transmit part or all of the energy generated by the main propelling charge to the projectile.

Another projectile embodiment is that of a projectile having a rocket type configuration, for use in recoilless weapons of the present invention having a smooth bore. Such a rocket-type projectile can be manufactured by conventional means and procedures. The different components of such projectile are generally permanently joined together. A projectile head carries the explosive or other material. An integral, tubular, hollow, perforated boom will be attached to the projectile head and have guiding or stabilizing fins on its rear end. A combustion chamber, filled with a solid propelling fuel or charge will be located within the inner bore of the boom. The exhaust of this secondary propelling charge, generally the exhaust nozzle of the inner combustion, is obturated by a relatively slow burning priming charge which will be ignited by the main priming charge contained in the remainder of the boom bore. After the projectile is out of the muzzle of the recoilless weapon, the secondary, slow-burning priming charge will be totally burned, at which time the solid propellant inside the inner combustion chamber will be ignited. This ignited solid propellant will blow the conventional primer affixed to the rear end of the boom out of same end, as in a conventional rocket-type projectile, impart a secondary thrust or boost to the projectile. The conventional primer mentioned above, lo-

cated in the rear end of the boom, ignites the main priming charge inside the boom upon firing, and the main priming charge flares out of the perforations on the boom body to ignite the main propelling charge located in the annular space between the boom and the cartridge case.

The cartridge cases of the cartridges of the present invention differ notably from the prior art recoilless weapon cartridge cases, in that the rearward gas escape is effected through only one large opening at the base of the case and being axial thereto. Generally, the cartridge case will be of metal, although non-metallic substitutes may be used therefor as known to the art. As mentioned previously, the main projectile propelling charge will be contained inside of the cartridge case, in the normal fashion.

The priming device may be the same as conventional primers used in cartridges having projectiles with a boom attached thereto (either permanently or separably). The priming device may also be in the form of a primer disk or disks which are affixed in suitable recesses within the gas escape opening of the cartridge case. In such situations, such recesses will provide surfaces on which the striker crushes the primer to ignite same.

Preferably, a gas check piece is fitted into the cartridge case gas escape opening. Such gas check piece will be a cylindrical metal piece having an axial bore therein, which functions as a gas check or seal in some variations of the cartridges of the present invention. Upon firing of the cartridge, the action of the gasses flowing through the gas escape opening in the cartridge case base, causes the gas check piece to slide out of the cartridge case base into a matching recess on the bolt face entrance to the bolt bore, to obturate the separation or space between the case base and the bolt face, thus providing a gas seal while the gasses are flowing through the case base into the bolt bore. In some variations of the cartridges of the present invention, this gas check piece may also transmit the blow from the striker portion of the piston or bolt to crush the priming disk. In such a variation, the priming disk would be located between the cartridge case gas escape opening innermost salient or recess and the inner surface of the gas check piece. In another variation, the priming disk could be located inside the gas check piece bore at the rearmost portion thereof, resting on a salient or recess similar to the one described above. In either embodiment, the bore of the gas check piece may be obturated by a thin combustible plastic protective disk, located directly on the primer disk, or perhaps by two protective disks when the primer disk is located deep within theinside of the gas escape opening in the cartridge case base. Alternatively, when the primer disk is located deep within the gas escape opening in the cartridge case base, such primer disk may be protected by a solid cylindrical plastic combustible protective plug.

DESCRIPTION OF THE DRAWINGS The present invention will be more readily understood with reference to the accompanying drawings, wherein:

FIG. 1 represents a view, partly in section, of a cartridge or round of ammunition.

FIG. 2 is a frontal view of the projectile support of FIG. 1.

FIG. 3 is a sectional view of the projectile support of FIG. 1.

FIG. 4 is a side view of the front part of the boom of FIG. 1.

FIG. 5 is a view, partly in section, of the projectile and boom of another embodiment of the cartridge of the present invention.

FIG. 6 is a partially sectioned view of yet another embodiment of the cartridge of this invention.

FIG. 7 is a rear view of the cartridge of FIG. 6.

FIGS. 8 and 9 are each a sectional view of the rear portion of the cartridge case representing another embodiment of the present invention.

FIG. 10 is a sectional view of the front part of the bolt and piston of the recoilless weapon of the present invention.

FIG. 11 is a sectional view of the bolt of the recoilless weapon.

FIG. 12 is a sectional view of another embodiment of the bolt of the present invention.

FIG. 13 is a sectional view of the piston and bolt of the present invention.

FIG. 14 is several sectional views of different embodiments of the striker portion of the piston.

FIG. 15 is a top view ofa different embodiment of the piston.

FIG. 16 is a cross-sectional view along lines AA of FIG. 15.

FIGS. 17 and 18 are sectional views of different embodiments of the front portion of the piston.

FIG. 19 is a front view of the striker portion of the piston of FIG. 18, taken along lines B-B.

FIG. 20 is a top view of another embodiment of the bolt of this invention.

FIGS. 21 and 22 are frontal views of the front portion of the bolt of FIG. 20, illustrating different embodiments of the locking lugs.

FIG. 23 is a top view of an alternative form of the piston of the present invention.

FIG. 24 is a perspective view of another embodiment of the bolt of the present invention.

FIG. 25 is a sectional view of the rear portion of the recoilless weapon.

FIG. 26 is a sectional view of the exhaust tube of the recoilless weapon.

FIG. 27 is a sectional view of a different embodiment of the rear end of the exhaust tube of the present invent1on.

FIG. 28 is a sectional view ofa different embodiment of the front end of the exhaust tube of the present invention.

FIG. 29 is a side view of one embodiment of the recoilless weapon of the present invention.

FIG. 30 is a top view of a recoilless weapon similar to that of FIG. 29, but illustrating yet another embodiment of the locking recess housing.

FIG. 31 is a side view of yet another recoilless weapon of the present invention.

FIG. 1 represents a sectional view of a cartridge 10 adapted to be utilized in the recoilless weapons described herein. The cartridge 10 consists of a projectile 12 having one or more rotating bands 14, a separable projectile support 16, having two or more sections fitted together and covering the front part of the perforated boom 18 having fins 20 on the rear end thereof.

The sections of the projectile support 16 separate from the projectile after leaving the muzzle of therecoilless weapon. Surrounding the projectile support 16 and boom 18 is a metal cartridge case 22, having an opening 24 at its base. The projectile 12 is fitted at least partly into the front end of the cartridge case 22. A circular metal gas check piece 26 is in sliding contact with the rear portion of the cartridge case 22. A circular combustible plastic disc 28 obturates a portion of opening 24 in the cartridge case base, between gas check piece 26 and the rear end of boom 18. A conventional priming device (not shown) is affixed to the rear end of the boom 18 to ignite a priming charge (not shown) inside of the boom. A main propelling charge (not shown) is located in the annular space between boom 18 and cartridge case 22.

When the priming device is struck by a striker or other primer activating device of the recoilless weapon, it ignites the priming charge inside of boom 18. The priming charge flares out of the multiple openings in the body of the boom 18 to ignite the main propelling charge in the annular space between boom 18 and cartridge case 22, applying energy to the projectile support 16 which transmits such energy to the projectile 12. The angled outside surfaces of the projectile support, i.e., the outside surfaces which point inwards toward the boom, may be at an angle of or less with the axis of the boom 18. In this variation of the cartridge of the present invention, the fins 20 on the boom 18 act only as guides to keep the boom stabilized inside the bore of the recoilless weapons barrel. Once the projectile 12 and projectile support 16 are through the muzzle of the gun, rotational energy will cause the sections of the projectile support 16, which sections are simply joined together over the front part of the boom 18, to come apart and be separated from the projectile, which will continue its trajectory alone.

FIG. 2 represents a frontal view of the projectile support 16 of FIG. 1. The projectile support consists of four quarters 30, 32, 34 and 36, which are simply joined together over the front part of boom 18 to constitute a separable unit, when freed of circumferential restriction upon leaving the gun muzzle. The purpose of the projectile support is to separably link the projectile and the boom and to impel the projectile forward under the force produced by the propellant charge.

FIG. 3 represents a sectional view of the projectile support 16, showing sections 30 and 32. The angled outside surface 38 can vary from the angle shown, to a 90 angle, or less, in relation to the axis of the boom. The rear end of projectile l2 fits into projectile recess 40, and the front end of boom 18 fits into recess 42, being encased by projectile support 16.

FIG. 4 shows the front part of boom 18, having a recess 44 over which the projectile support 16 fits. The boom has a large number of perforations extending into the inner bore thereof.

FIG. 5 represents a view, partly in section, of another variation of the projectile and boom of the cartridge of this invention. The projectile unit 46 represented by FIG. 5 is more in the nature of a rocket, with a secondary thrust or boost imparted to the projectile unit after it has left the muzzle of the recoilless weapon. Projectile unit 46 is a complete unit, which can be made integral or whole, or can be fabricated from several parts permanently assembled into a whole unit, and comprises projectile head 48 containing the explosive or detonating element of the projectile, hollow boom 50 containing perforations 52 along its main body, and an inner combustion chamber 54 having a rearward exhaust nozzle 56. The space 58 between the perforated boom 50 and combustion chamber 54 is filled with a priming charge (not shown). Slow priming charge 60 is located within the combustion chambers exhaust nozzle 56. A solid fuel charge (not shown) is located within combustion chamber 54. Conventional primer 62 is located in the rear end of boom 50, and fins 64 are attached to the rear part of boom 50.

Projectile unit 46 is encased in the metallic cartridge case, as illustrated in FIG. 1, with the cartridge case containing a main propellant charge. Projectile unit 46 is designed to be utilized in recoilless weapons having smooth bore barrels, with the projectile stabilized in its trajectory by the boom and boom fins.

In operation, the primer 62 is struck and ignited by a striking element of the recoilless weapon. The ignition of the primer 62 ignites the priming charge contained in space 58, which flares out of perforations 52 along the main body of boom 50 to ignite the main propelling charge. The ignition of the primer charge also ignites slow priming charge 60, which burns at a rate such that it does not ignite the solid fuel charge located within combustion chamber 54 until projectile unit 46 has left the muzzle of therecoilless weapon. Once this solid fuel charge is ignited, it flares inside the boom, knocking conventional primer 62 out the rear end thereof, thrusting out of the rear end of the projectile unit 46 giving it an extra impulse. Perforations 52 on the booms body may vary in form to provide better air entrance once the projectile is in flight and the solid fuel secondary charge is ignited and sucks air into the inner rear part of the boom.

FIG. 6 represents a partially sectional view of another type of cartridge 66 to be utilized in the recoilless weapons described herein. The cartridge 66 consists of a projectile 68, a metallic case 70 having an opening 72 at its rear end or base, opening 72 being circular and axial with the cartridge. Inside of cartridge case 70 is space 74, which contains a propelling charge (not shown). A primer 76 is located in opening 72, and primer 76 is capped by protective disc 78 made of polyethylene or other plastic combustible material. The inner rear surfaces 80 of the cartridge case 70 may be varied in angle in order to control the rearward thrust of the cartridge case after firing.

Upon firing cartridge 66, protective disc 78 is struck by the striker mechanism of the recoilless weapon, crushing and igniting primer 76. Ignition of primer 76 ignites the propelling charge located in space 74, expelling projectile 68 out of cartridge case 70 and down the barrel of the recoilless weapon. At the same time, a rearward thrust againstsurfaces 80 occurs. A portion .of the gases produced by the propelling charge is passed through opening 72 (primer 76 and protective disc 78 are consumed by the ignition of the primer and the propelling charge) and into the bore of the bolt of the recoilless weapon, as described hereinafter.

FIG. 7 represents a rear view of the cartridge. of FIG. 6 (after firing). Gases escape rearwards through opening 72 into the breech mechanism. The priming disc rests upon recess 82, against which the striker will crush the primer to ignite same.

FIG. 8 represents a second view of the rear portion of a cartridge case illustrating another variation of the present invention. Case 84 is similar to case of FIG. 6 in that it contains, in its front opening, a projectile, and in its rear end it has an axial and circular opening 86 to permit the escape of gases. A hollow cylindrical gas-check piece 88 is inserted in rear opening 86, having a front surface resting on circular primer 90. The gas-check piece 88 transmits a blow from the striker head of a piston, which strikes the rear of gas-check piece 88, to crush the primer 90 against shoulder 92, thus igniting the propelling charge contained within case 84. The metal cylindrical, hollow gas-check piece 88 slides out of its position inside the base 84 by action of gases on its inner surface 94, thus functioning as an effective gas check against the bolt or breech mechanism face. The'angled inside surfaces 96 of case 94 may be varied in angle and/or configuration in order to reduce or increase the reaction of the cartridge case against the bolt or breech face, such reaction caused by the pressure of gases acting on surface 96. The cartridge may have a circular combustible plastic disc 98 in the rear of opening 86. Alternatively, such disc may be located between the gas-check piece 88 and the primer 90, or two such protective circular combustible discs may be used, one at the front and one at the rear of opening 86. In another embodiment, a solid combustible plastic cylinder may be inserted inside of gascheck member 88, occupying the space between primer 90 and the rear end of the gas-check piece, flush with the base of cartridge 84.

FIG. 9 represents a sectional view of the rear part of yet another variation of the cartridge of the present invention. The cartridge case 100 has an axial opening 102 in its base, similar to the cartridge case openings of FIGS. 6 and 8. Circular primer 104 is similar to the primers of FIG. 8. The primer 104 rests inside of a cylindrical, hollow metallic gas-check piece 106 inserted inside of opening 102 in the rear end of the cartridge case. Protective combustible plastic disc 108 overlies the primer and is rearward thereof. Gas-check piece 106 is restrained against further travel towards the interior of case 100 by shoulder 110. Primer 104 rests upon shoulder 112 of gas-check piece 106.

Upon firing, a striker strikes and crushes the primer against recess 112, detonating the primer and thus igniting the propelling charge contained inside of case 100. The rearward thrust of the gases escaping through opening 102 into the bore of the bolt of the recoilless weapon acting against surface 114 of gas-check piece 106, causes the gas-check piece to move slightly out of the case into a corresponding recess in the bolt or breech face, thereby providing a suitable gas check between the cartridge base surface and the bolt face. This operation of the gas check is similar to the function of gas-check piece 26 of FIG. 1. Angled surfaces 116 can be varied in size, angle, and configuration, similar to surfaces 96 of FIG. 8.

FIG. 10 is a sectional view of the rear part of the firing chamber and the front part of the breech or bolt of the recoilless weapon of the present invention. The cartridge 118 is shown in the firing chamber defined by barrel 120. Movable, axially reciprocating hollow bolt 122 is located rearward of barrel 120, and has a hollow, axial bolt bore 124 therein. Piston 126 is located within bolt bore 124, and defines axial piston bore 128. Openings 130 interconnect bolt bore 124 and piston bore 128, and openings 130 may be as shown or at an angle of more than 90 degrees in relation to the axis of the piston 126. Piston 126 contains several circular recesses 132 of variable width and depth, rearward of openings 130. Recesses 132 may contain grease or other suitable material to seal the space between the rear portion of piston 126 and the rear portion of bolt 122, to prevent gas escape from bolt bore 124 backwards into the recoilless weapon receiver. The distance a, which can vary for each type of cartridge for which the weapon is designed, is the distance the gas-check piece 134, such as illustrated in FIGS. 1, 8 and 9, slides out of case 118 into the face of bolt 122, being restrained by recess 136 at the opening to bolt bore 124. The front face 138 of the piston 126 acts as a striker, crushing the primer upon firing of the weapon.

Upon firing and ignition of the propelling charge within cartridge 118, gases escape through the rear circular opening in the base of cartridge 118, through gascheck piece 134, to enter the bolt through its circular, axial opening or bore 124. After pushing the striker or front face 138 of the piston rearwards far enough (this serves to cock the piston and to unlock the bolt, if the bolt is of the positive locked or hesitation locked variations) the gases flow into the main cylindrical hollow or bore 124 of the bolt 122, pass through openings 130 in piston 126 to the piston bore 128 and thence rearwards through piston bore 128.

FIG. 10 represents the instant after firing of the recoilless weapon when the gases have forced gas-check piece 134 rearward into engagement with recess 136, to seal the space between cartridge 118 and bolt 122, after the gases have acted upon the front face of piston 126 to drive the piston rearwards. The protective combustible plastic disc has been consumed.

FIG. 11 represents a blow-back" bolt design which is one embodiment of the present invention. The bolt 140 has a conventional extractor 142. The bolt 140, which may be of various outside configurations, such as cylindrical, square, or the like, has a cylindrical, axial bore 144 therein. Exhaust tube 146 is located at the rear of bolt 140, and has a bore 148 therein in which the rear end of the bolt 140, or a tubular estension thereof, is inserted. Exhaust tube 146 is affixed to the rear open end of the recoilless weapon receiver (not shown). Bolt recoil spring 150 is compressed between shoulder 152 of bolt 140 and the exhaust tube 146 when the bolt moves rearward. A cocking stud (not shown) fits into cocking stud recess 154. A sear (not shown) fits into sear recess 156 to engage and hold the bolt back in the receiver in a cocked position, as conventional in blow-back bolt type firearms. Bolt 140 is held in its forward position, closing the firing chamber after firing, and before the gases react upon the face of the bolt, only by the pressure exerted by bolt recoiled spring 150.

Conventional plunger type ejector 158 has a retaining stud 160 and spring 162. The cartridge case (not shown) fits into bolt face recess 164. Striker 166 is affixed to the front of bolt 140, permitting gas flow through the striker into the bolt bore 144, and serves to strike, or crush, the cartridge primer upon firing. This type of firing or striker mechanism may be screwed in or otherwise attached to bolt 140 in order that, when necessary, the striker 166 may be readily removed and replaced. This type of striker may be utilized with the cartridges described in FIGS. 6, 8 and 9.

It will be appreciated from the foregoing description that FIG. 11 represents the type of bolt which fires from an open bolt position. Gases escaping through the cartridge case opening pass through striker 166, into bolt bore 144. The gases continue their rearward flow through bolt bore 144 into exhaust tube bore 148. The gases then pass out of the exhaust tube through venturi or other opening or openings (not shown). Since exhaust tube 146 is affixed to the rear open end of the firearm receiver, the reaction caused between gases exiting from the exhaust tube is transmitted directly to the frame of the weapon, thus counteracting the recoil. The action of the gases upon the front face of bolt forces the bolt rearward, sliding into exhaust tube bore 148 and compressing bolt recoil spring 150. When bolt 140 has completed its rearward travel, the compressed bolt recoil spring 150 forces the bolt forward into its cocked position, wherein a sear engages sear recess 156, or, if the sear is held down in the fire position, the bolt travels forward to strike and ignite the primer on the next round of ammunition.

FIG. 12 illustrates another variation of the blow back or unlocked type bolt design. Bolt 168 is similar to bolt 140 of FIG. 11, but varies in that bolt 168 is an unlocked bolt that fires from a closed bolt position. Movable, cylindrical, hollow piston 170 is contained within the bolt. Cocking stud 172 engages piston 170 through longitudinal opening 174 in bolt 168. Bolt recoil spring 176 and piston recoil spring 178 are located rearwards of the bolt and piston, respectively. Exhaust tube 180 defines exhaust tube bore 182, which is in communication with the bore 184 of piston 170.

The cartridge case base (not shown) fits into recess 186 in the face of bolt 168. The circular front surface 188 of the piston acts as a striker. Piston bore 184 contains a chamber 190 having inner surfaces 192 at the rear thereof. Cocking sear 194 is located within a recess 196 in the rear end of the body of the bolt 168. The sear can engage piston 170 in circumferential, or circular, surfaces 198 (which is the same recess as that in which cocking stud 172 acts). Cocking stud 172, which moves within opening 174 in bolt 168, engages surface 200 at a certain point of its rearward travel and thereafter causes the bolt 168 to move rearward. Conventional plunger type ejector 202 is similar to ejector 158 of FIG. 11.

Operation of a recoilless weapon utilizing the bolt and piston arrangement of FIG. 12 is started by disengagement of sear 194 from piston recess 198, allowing piston 170 to travel forward under the impulse of piston recoil spring 178. Striker 188 on piston 170 strikes and ignites the primer of a cartridge held in recess 186. Exhaust gases pass through the axial rear opening of the cartridge into piston bore 184 and inner chamber 190. The gases expand in chamber 190 and act upon inner surface 192 of the chamber, causing the piston 170 to move rearwards and cock itself by means of cocking sear 194 engaging circular recess 198. Cocking stud 172 engages the body of bolt 168 when it reaches surface 200, causing the bolt to move rearwards, compressing both recoil springs 176 and 178, extracting the spent cartridge case, ejecting the cartridge case, and reaching the full back position, and then action of the bolt recoil spring 176 starts another cycle forward, stripping a cartridge from the conventional magazine (not shown), loading the cartridge into the firing chamber (not shown). After the cocking sear 194 is activated by the firing mechanism, freeing the piston from its cocked position, with the piston moving forward under pressure of its recoil spring 178, another firing cycle is started.

FIG. 13 illustrates yet another type of bolt or breech mechanism. The chamber end of barrel 204 contains cartridge 206. Bolt 208 defines bore 210 passing axially therethrough. Piston 212, having grease recesses 214, is within bolt bore 210. Conventional extractor 216 and conventional ejector 218 are at the front end of bolt 208. Angled inner surface 220 of bolt 208 may vary in inclination according to the axis of the bolt bore. The front part 222 of piston 212 acts as a striker. Surface 224 of the piston rests on the inner surface 220 of bolt 208 when in the fired position. The piston contains an inner bore 226, interconnected to bolt bore 210 by openings 228, which openings may be in any of the angles shown. Recesses 230 out into the outer part of the piston thrust out locking rollers 232, which are illustrated in the unlocked position (the dotted lines illustrate the same rollers in the locked position). When in the locked position, the rollers engage locking surfaces 234 and 236. Additional sets of locking rollers and corresponding locking surfaces or recesses built into, or fixed to, the receiver or a barrel extension may be used, as desired. Longitudinal narrow slot 238 is in the body of bolt 208, permitting cocking stud 240 to engage piston 212. Cocking stud 240 may act on the end of bolt 208 to push the bolt rearwards to start the firing cycle. This cocking stud 240 also cocks piston 212, in a manner similar to that described for the embodiment of FIG. 12, by having sear 242 engage piston sear recess 244. The sear 242 is located in a suitable slot 246 in the rear end of bolt 208, and is biased by sear spring 248. The sear may have a bearing surface protruding from the bolt body, as shown, or it may be completely concealed, as illustrated in FIG. 12. Bolt recoil spring 250 and piston recoil spring 252 both rest on the front surface of exhaust tube 254. The rear end of piston 212 is inserted in the inner opening or bore 256 of exhaust tube 254. The tolerances permitted on the locking surfaces 234, 236, and the angles of these surfaces, vary according to the size of the rollers utilized, which are in turn related to the type of and size of cartridge used in the firearm. The tolerances must be sufficient, in any event, to permit a certain play of the rollers to facilitate unlocking, e.g., to permit the rollers to slide back into recesses in the bolt body. Therefore, the bolt will also have a little play back and forth while in the locked position.

In operation, the bolt and piston will be in the general arrangement illustrated just prior to firing the first round of ammunition. A trigger mechanism disengages sear 242 from sear recess 244, allowing the piston 212 to move forward under the impulse of piston recoil spring 252. The forward motion of piston 212 during this portion ofthe firing cycle pushes rollers 232 into recesses in the body of bolt 208 and into engagement with locking surfaces 234, 236. The piston continues its forward travel until surface 224 meets surface 220 and striker 222 crushes the primer of cartridge 206. Detonation of the primer ignites the main propelling charge of cartridge 206 and a portion of the exhaust gases exit through the rear axial bore thereof, as explained previously with regard to FIGS. 1-9. The action of these gases upon the front face of striker 222 pushes piston 212 rearward. At a predetermined point in rearward travel, piston recesses 230 pass over rollers 232, allowing the rollers to move into the unlocked position.

Cocking stud 240 engages the rear end of slot 238 of the bolt 208, pushing the bolt back with piston 212, compressing bolt recoil spring 250 and piston recoil spring 252 against the front surface of exhaust tube 254. The exhaust gases pass into the main bore 210 of bolt 208 when striker 222 moves past surface 220, and then the gases pass through openings 228 into piston bore 226. The rear end of piston 212 slides into exhaust tube bore 256 and the gases passing through piston bore 226 move through exhaust tube bore 256 and exit to the atmosphere through a venturi or other opening or openings (not shown). After the gas pressure inside of bolt bore 210 and piston bore 226 has decreased, the action of bolt recoil spring 250 and piston recoil spring 252 moves the bolt and piston, respectively, forward. In its forward travel the piston 212 reaches its cocked position when spring 248 pushes sear 242 into piston sear recess 244 to engage the piston, and the mechanism is ready for the next firing cycle.

Several sectional views of the front or striker part of the piston are illustrated in FIG. 14. Any of the various embodiments illustrated could be used for striker 222 of FIG. 13, or striker 138 of FIG. 10, for instance. FIG. 14(a) illustrates an embodiment with a flat striking surface 258. FIG. 14(b) illustrates a striker having a concave frontal part 260 and a flat rim 262 for crushing the cartridge primer. FIG. 14(0) represents a striker with a flat front 264 having a protruding pin 266, which may be integrally attached or otherwise affixed to the striker. This embodiment is suitable for use in firearms utilizing cartridges having normal, or conventional, primers, such as discussed in relation to FIGS. 1 and 5. FIG. 14(d) illustrates still another form of the striker having a concave frontal part 268 and a serrated striking rim 270.

FIG. 15 represents a top view of another embodiment of the piston. Piston 272 has a striker 274 located at the front end thereof. Multiple openings or perforations 276 (similar to openings 228 of FIG. 13) allow the passage of gasses from the bolt bore (not shown) to the piston bore 278. The outer portion of the middle part of piston 272 has circular recesses 280 which contain heavy grease or other suitable sealants or piston rings, in order to prevent excess gas seepage from the bolt bore into the receiver. Flat surfaces 282, 284, are located rearwards of recesses 280. Rollers, such as rollers 232 of FIG. 13, contact surfaces 282, 284 when in the unlocked position, e.g. when the rollers are totally within their bolt body recesses. Angled surfaces 286, 288, just rearwards of flat surfaces 282, 284, push the locking rollers (not shown) out of the bolt body into the corresponding locking recesses of the receiver or barrel extension when the piston moves forward in the bolt bore during the firing cycle. The locking rollers are pushed out of the bolt body only after the bolt is fully closed, thus locking the bolt before the primer is struck. Recess 290 in the piston receives the cocking stud (not shown) similar to the embodiments described in FIGS. 12 and 13. A piston extension 292 extends rearward of the piston and is inserted into the exhaust tube (not shown) in a manner similar to that shown in FIG. 13. The piston recoil spring (not shown) is coiled around piston extension 292. This variation of the piston of the present invention may be manufactured from a single piece of metal, or alternatively, may be manufactured from separate pieces which are screwed or otherwise affixed together.

FIG. 16 represents a cross-sectional view of the piston 272 of FIG. 15, taken along lines AA. 294 is the sear recess in piston 272.

FIG. 17 represents another form which the front portion of the piston may take. The front portion of piston 296 has a striker 298 at the front thereof. Piston bore 300 is connected by gas openings 302 to the bolt bore (not shown).

FIG. 18 represents yet another embodiment of the front portion of the piston of this invention. The piston 304 has a striker rim 306 at the front thereof, a piston bore 308 and gas openings 310. The function of these parts is the same as the corresponding parts of the piston front portion of FIG. 17.

FIG. 19 is a frontal view of the piston of FIG. 18, taken along lines B-B.

FIG. 20 is a top view of another variation of a bolt assembly of the present invention. In this embodiment, the bolt 312 is of round or cylindrical shape. Bolt 312 has two frontal locking lu'gs 314, 316 which, by a clockwise or counterclockwise turn of the bolt, engage in corresponding recesses in the rear end of the barrel or of a barrel rear extension (not shown). This type of frontal locking is conventional, but the manner in which the bolt is rotated to engage such lugs in the corresponding recesses is not known to the art. Locking stud 318 is inserted in piston 320. The locking stud moves inside of a longitudinal, angled locking slot 322 on the main body of bolt 312. The locking stud 318 moves inside a transverse or longitudinal opening in the receiver (not shown) so that locking stud 318 can have only axial, or longitudinal motion. The piston has an inner bore 324 and a piston recoil spring 326.

In operation, the direct action of escaping gases on the front surface of the piston causes the piston 320 to move violently rearwards. Locking stud 318, which is affixed to the piston, moves rearward with the piston. As mentioned above, the locking stud can move only in a longitudinal direction, due to the guidance of the longitudinal opening in the receiver. The angled portion 328 of the locking slot 322 causes rotation of the bolt as locking stud 318 travels along the angled surface. When the locking stud reaches the next section of the locking slot, wherein the locking stud again moves parallel to the axis of the piston bore, the bolt has rotated an amount sufficient to unlock locking lugs 314, 316, and the bolt is then unlocked. The locking stud continues its travel in locking slot 322 until it reaches surface 330, whereupon it strikes the bolt body and pushes the unlocked bolt rearwards to extract and eject the spent cartridge case and compress the bolt recoil spring. After the gas pressure has decreased inside of the bolt mechanism, the pressure of the bolt and piston recoil springs starts to move the bolt and piston, respectively, forward to complete the firing cycle. The piston will be cocked on its travel forward by a sear arrangement (not shown) of the type described in FIG. 13, for instance, The piston will be engaged by the sear mechanism generally at the time the forward motion of the piston has caused the locking stud 318 to pass through the angled portion 328 of the locking slot 322 to cause the bolt to rotate on its axis and lock itself. Thus, upon firing, the piston will travel the distance b to crush the cartridge primer. The locking stud 318 is inserted into the locking slot 322 by way of slot entry 332. Locking lugs 314, 316 generally have their rear, or locking, surfaces at a slight angle (which is in current fashion) to permit faster locking time, and smoother locking and primary case extraction. The type of bolt described could use any of the pistons described herein previously, as well as the piston illustrated in FIG. 23, described hereinafter.

FIG. 21 represents a frontal view of a bolt similar to that described in FIG. 20, with a different type of locking lug. The bolt 348 has a number of locking lugs 350 thereon. Extractor 352 and ejector slot 354 are on the bolt front face. A cartridge case head recess 356 is inside of bolt face 358. Bolt bore 360 is axially centered in the bolt. Locking stud 362 is attached to the main body of bolt 348.

FIG. 22 is yet another view of the front of a bolt similar to the bolt of FIG. 20, with a different embodiment of the locking lug design. Bolt 364 has locking lugs 366, 368, extractor 370, ejector slot 372, cartridge case head recess 374, bolt face 376, bolt bore 378 and locking stud 380, with all of the parts having the same function as the corresponding part of FIG. 21.

FIG. 23 represents a top view of another embodiment of the piston of the present invention. Piston 334 could be used in the turning bolt design described in FIG. 20, for instance. The striker 336 is located at the front of the piston. Gas openings 338 communicate with the piston bore 340. Gas openings 338 may be of various forms, such as the forms shown in FIGS. 13, 17 and 18. Locking stud 342 is similar to locking stud 318 of FIG. 20. A circular recess 344 is cut into the rear end of that portion of the piston which goes inside the bolt bore, to engage the sear (not shown) to cock or arm the piston. Recesses 346 at the front portion of the piston hold grease or other gas sealing means.

FIG. 24 is a perspective view of a bolt assembly which could be used in the recoilless weapons of the present invention, and the bolt and piston could be similar to those of FIG. 13, for instance. Bolt assembly 382 includes a bolt 384 having recesses containing cylindrical locking parts, or rollers, 386. As illustrated, the rollers are thrust out of the bolt 384 a bit more than when their position would be in a fully locked position. Bolt recoil springs 388 (only one is shown) are around bolt guides 390, which pass through shoulders 392 on bolt 384. Bolt 384 has concave channels 394 along its top edges (such channels could also be along the bottom edges) to permit full insertion into such channels of the recoil spring guides 390 as the bolt 384 moves rearward to compress recoil spring 388. Piston 396 extends rearward of bolt 384 (the piston recoil spring is not shown). The bolt face 398 contains an ejector 400, a case head recess 402, a bolt bore 404 and a conventional extractor 406. This type of bolt will have a sear arrangement (not shown) on its bottom rear part, as discribed previously.

FIG. 25 represents a side view, partly in section, of the rear portion of the recoilless weapon. The weapon 408 includes a receiver 410, a bolt 412 containing a piston sear 414 (shown by dotted lines). The bolt recoil spring 416 and piston recoil spring 418 both surround the rear end of piston 420 (or piston extension tube). The rear end of piston 420 is inserted in exhaust tube 422. Exhaust tube 422 is screwed or otherwise fixedly attached to the open rear end of receiver 410. The exhaust tube has an outwardly angled exit 424 at its rear end surrounding gas exit opening 426. A shoulder support 428 is affixed to the bottom rear end of the receiver 410, with the shoulder support 428 reinforced by perforated reinforcing web 430. The shoulder support 428 may be a curved, perforated metal sheet which is soldered or otherwise permanently affixed to the perforated web 430. The perforations in web 430, which is intended to provide rigity to the shoulder support, serves to reduce the weight thereof, and can also function as a sling slot. A trigger mechanism housing 432 is held to receiver 410 by pins 434, 436. Pistol grip 438 is attached to trigger mechanism house 432 by pis-v tol grip retaining screw stud 440 and pistol grip retaining screw bushing 442. Trigger guard 444 surrounds trigger 446. Sear actuator 448 engages sear 414 when trigger 446 is pulled. Stud 450 serves-as a safety and as a selector for automatic or semiautomatic firing. When pin 434 is removed, the trigger housing pivots about pin 436 to permit inspection thereof. The trigger, trigger mechanism housing and arrangement and pistol grip are all conventional.

The exhaust tube 422 may have other forms than that illustrated. It may have various outside configurations, such as square or round, with a round inside bore, which will be axially aligned with the piston axis. The exhaust tube may be screwed to the rear end of the receiver, although other means of affixing same may be utilized, especially in the case where the receiver is of square tubular form. The gas exit opening piece is preferably removable and replaceable, and conveniently may be of the screw-on type.

FIG. 26 represents another embodiment of the exhaust tube which may be used in the recoilless weapon of this invention. Exhaust tube 452 is similar to exhaust tube 422 of FIG. 25, except for the rear portion thereof. An internally threaded collar 454 allows exhaust tube 452 to be screwed to the receiver rearend (not shown). Gas exit piece 456 defines gas exit opening 458. Gas exit 456 is screwed into exhaust tube 452, and is readily removable and replaceable. Bolt and piston recoil springs (not shown) rest on exhaust tube surface 460. Exhaust tube bore 462 is axially located in the interior of the exhaust tube, and rear end of the piston or piston extension (not shown) is inserted in this bore.

FIG. 27 represents another form of the exhaust tube. Exhaust tube 464 has a bore 466, recoil spring'receiving surface 468, collar 470, and gas exit piece 472 defining gas exit opening 474. Thegas exit piece 472 is located in recess 476 at the rear end of exhausttube 464. The gas exit piece 472 is less likely to be damaged through external blows when'so recessed.

FIG. 28 represents yet another form of the exhaust tube which can be used in the recoilless-weapon of the present invention. In some variations of therecoilless weapon, the bolt recoil spring may be located inside a tube at the top of the barrel. In this situation, the rear end of the bolt (not shown) can strike, at the end of its rearward travel, surface 478 of bolt recoil absorber 480. Rearward movement of bolt recoil absorber 480 compresses bolt recoil absorber spring-482 against stop 484, which also functions as a front guide for exhaust tube 486. The bolt recoil absorber is held in place by retaining ring 488.

FIG. 29 illustrates one embodiment of the recoilless weapon of this invention. Recoilless weapon 490 has a long square profile tube receiver 492 (which could also be of roundcross section) open at both ends. Conventional rear sighting apparatus 494 and front sighting apparatus 496 serve to align the weapon on the target.

Locking recess housings 498, 500 are in the top and bottom of the receiver, surrounding the locking recesses when the bolt is of the hesitation-locked type design. The locking recess housings 498, 500 are affixed to the receiver by current methods known to gunsmiths, such as soldering, for example. The locking recesses could be located in the barrel or in a barrel extension, if desired. The rear portion 502 of the exhaust tube is attached to the receiver 492 and surrounds the final gas exit opening or openings, generally indicated at 504. A shoulder support 506 is located at the rear of the weapon. The cocking stud 508 moves in cocking stud guide longitudinal opening 510. The cocking stud 508 can be inserted or removed through a cocking stud insertion hole 512. The trigger mechanism housing 514 is held to receiver 592 by pins 516, 518. Pistol grip 520 and trigger guard 522 are fixed to the trigger mechanism housing 514. Trigger 524 is within the trigger guard. Conventional magazine 526 is released by magazine release lever 528. The receiver contains a number of openings 530 for cooling the barrel 532. Bayonet stud 534 is located at the bottom of the front portion of the receiver. Barrel cap 536 is affixed to the front of receiver 492. The barrel may be fitted or affixed to the receiver by any of the current methods known to the art.

FIG. 30 represents a top view of a firearm similar to that of FIG. 31, with the locking recesses arranged in a different manner. The weapon 538 has a receiver 540 having a conventional ejection port window 542 (shown in the closed position). Right locking recess housing 544 and left locking recess housing 546 are located in the sides of receiver 540. Cocking stud 548 is also located in the side of the receiver. Conventional rear sight 494 and from sight 496 are similar to those of the weapon of FIG. 29, as is exhaust tube rear portion 502 and gas exit opening or openings 504. The barrel ventillation opening 530 may be of various shapes such as round, elongated and the like. Barrel 532 is held to receiver 540 by barrel holding cap 550.

FIG. 31 is another version of the recoilless weapon of the present invention. The recoilless weapon 552 has a tubular, round receiver 554 (which could be of square or other convenient profile form). Conventional rear sighting apparatus 556 and front sighting apparatus 558 serve to align the weapon on the target. Cocking stud 560 travels in longitudinal codking stud guide 562 in receiver 564. Exhaust tube 564 is affixed to receiver 554 by means of exhaust tube cap 566 (an enlarged opening .for the cocking stud 560 to enter its receiver guide 562 is located-under exhaust tube cap 566). Exhaust tube collar 568 is similar to collar 454 of FIG. 26 and collar 470 of FIG. 27, and contains removable, replaceable final gas exit pieces. The final gas exit opening or openings is generally in the area shown at 570. Shoulder support 572 is located toward the rear of the weapon, with trigger mechanism housing 574 located forward thereof and held to receiver 554 by pins 576, 578. Pistol grip 580 and trigger guard 582 are attached to the bottom portion of trigger mechanism housing 574 with trigger 584 inside of trigger guard 582. Magazine 586 is released from the weapon by magazine release lever 588. Barrel 590 protrudes past receiver 554 and has a front sighting apparatus 558 and bayonet stud 592 attached thereto. Receiver cap 594 affixes and aligns the barrel in receiver 554.

It will be appreciated from the above description that the recoilless rifle of the present invention, and the round of ammunition therefore, are highly useful in the military firearms field, and also in the civilian or sporting firearms field.

In the military versions of this firearm, which versions are generally capable of full automatic fire, the present invention meets a long felt need for a light, controllable, automatic firing infantry weapons system utilizing powerful cartridges or even extra powerful cartridges. The current so-called assault rifles manufactured today do reduce recoil and make such rifles more controllable in fully automatic fire, but only at a very heavy cost. Either the caliber of the cartridge is reduced, such as in the controversial AR-l6 (Cal. .223) or else the cartridge propelling charge is reduced to render the weapon more controllable in fully automatic fire usage, resulting in a rather inefficient cartridge (this approach will be found in, e.g. Spain or Japan, where the regular 7.62 NATO cartridge is of reduce propelling charge.) A full propelling charge, or especially an extra powerful round of relatively the dimensions of the common 7.62 NATO round, but of recoilless nature, would permit total controllable automatic fire which would be an extremely valuable military asset. Such rounds of ammunition, and weapons for utilizing the same, are provided by the present invention.

Recoilless weapons of the present invention, and especially the receiver parts thereof, can be made of extremely light and non-strategic materials, more adapted to current mass manufacturing processes. The light weight and high cannon fire rate of the recoilless weapons of the present invention should be most welcome in combat aircraft where conventional, currently available ordnance places a heavy requirement on the aircraft by the additional weight added through the necessary reinforcing of frames and cannon locations. Thus, the recoilless weapon of the present invention should find considerable utility in combat aircraft.

In armored vehicles, the cannon mounted on the vehicle consumes a considerable amount of weight and space, and a cannon designed according to the present invention, when used on tanks, for instance, could allow a more adequate design distribution of the turret interior space. Other advantages of the present invention in the military firearms field are numerous and widespread and are believed clear from the preceeding description.

In the civilian or sporting firearms field, the firearms generally do not have automatic fire capability. However, the advantages of the present invention will be readily appreciated when considering the requirements of hunting large, dangerous game. In such situations, the hunter desires an extremely light, recoilless firearm, utilizing an extremely potent cartridge with a very heavy bullet. Available weapons have just not met all of the above criteria. For instance, a big game hunter experiences considerable hardships when shooting a rhinoceros with a conventional weapon considered adequate for this purpose, which weapon will be, for instance, 12 20 lb. double rifle utilizing a .600 Nitro express cartridge. Such a rifle recoils excessively. In such a situation, the advantages of the weapons of the present invention are believed clear.

What is claimed is:

I. An automatic firearm of the reduced recoil type comprising: a receiver; a barrel mounted to said receiver and at least partly defining at its rear end a firing chamber loadable with a round of ammunition adapted to discharge gas rearwardly thereof on being fired; bolt means cooperable with the rearward end of said firing chamber and reciprocable in said receiver to extract from said chamber a spent round of ammunition, load thereinto a fresh round and cock said firearm for another firing cycle, said bolt means having a gas passageway extending longitudinally therethrough; yieldable means for urging said bolt means forwardly towards said firing chamber, said bolt means being urged rearwardly of said firing chamber by gas pressure on said bolt means developed in said firing chamber; a reciprocable piston in said passageway and defining a second gas passageway through said piston in communication with said exhaust tube means, and, during at least a portion of the firing of said firearm, with said passageway, said piston being urged rearwardly by gas pressure developed in said firing chamber; and gas exhaust tube means associated with said receiver for receiving gas from said passageway and discharging said gas rearwardly of said firearm.

2. The firearm of claim 1 including sear means associated with said bolt to releasably retain said piston in a rearward position.

3. A firearm as defined in claim 1 including second yieldable means for urging said piston forwardly.

4. A firearm as defined in claim 3 wherein said yieldable means is a bolt recoil spring means and said second yieldable means is a piston recoil spring means.

5. A firearm as defined in claim 4 including cocking means associated with said piston for engaging said bolt after said piston has moved rearward a predetermined distance to move said bolt rearwards and to cock said firearm.

6. An automatic firearm of the reduced recoil locked bolt type comprising: a receiver; a barrel mounted to said receiver and at least partly defining at its rear end a firing chamber loadable with a round of ammunition adapted to discharge gas rearwardly thereof on being fired; bolt means cooperable with the rearward end of said firing chamber and reciprocable in said receiver to extract from said chamber a spent round of ammunition, load thereinto a fresh round and cock said firearm for another firing cycle, said bolt means having a gas passageway extending longitudinally therethrough; yieldable means for urging said bolt means forwardly towards said firing chamber, said bolt means being urged rearwardly of said firing chamber by gas pressure on said bolt means developed in said firing chamber; a reciprocable piston at least partly within said passageway and defining a second passageway extending through said piston in communication with said exhaust tube means and with said passageway during at least a portion of the firing of said firearm; and releasable locking means to lock said bolt in its forward position and releasable by travel of said piston rearwardly a predetermined distance; and gas exhaust tube means associated with said receiver for receiving gas from said passageway and discharging said gas rearwardly of said firearm.

7. A firearm as defined in claim 6 including sear means associated with said bolt for releasably retaining said piston in a rearward position.

8. A firearm as defined in claim 7 including cocking means associated with said piston for engaging said bolt after said piston has moved rearward a predetermined said cocking means attached to said piston and extending through said bolt slot and said receiver slot, whereby reciprocable movement of said piston causes corresponding movement of said cocking means, within said bolt slot and rotation of said bolt to lock and release said bolt by said locking means.

a: a: a: 

1. An automatic firearm of the reduced recoil type comprising: a receiver; a barrel mounted to said receiver and at least partly defining at its rear end a firing chamber loadable with a round of ammunition adapted to discharge gas rearwardly thereof on being fired; bolt means cooperable with the rearward end of said firing chamber and reciprocable in said receiver to extract from said chamber a spent round of ammunition, load thereinto a fresh round and cock said firearm for another firing cycle, said bolt means having a gas passageway extending longitudinally therethrough; yieldable means for urging said bolt means forwardly towards said firing chamber, said bolt means being urged rearwardly of said firing chamber by gas pressure on said bolt means developed in said firing chamber; a reciprocable piston in said passageway and defining a second gas passageway through said piston in communication with said exhaust tube means, and, during at least a portion of the firing of said firearm, with said passageway, said piston being urged rearwardly by gas pressure developed in said firing chamber; and gas exhaust tube means associated with said receiver for receiving gas from said passageway and discharging said gas rearwardly of said firearm.
 2. The firearm of claim 1 including sear means associated with said bolt to releasably retain said piston in a rearward position.
 3. A firearm as defined in claim 1 including second yieldable means for urging said piston forwardly.
 4. A firearm as defined in claim 3 wherein said yieldable means is a bolt recoil spring means and said second yieldable means is a piston recoil spring means.
 5. A firearm as defined in claim 4 including cocking means associated with said piston for engaging said bolt after said piston has moved rearward a predetermined distance to move said bolt rearwards and to cock said firearm.
 6. An automatic firearm of the reduced recoil locked bolt type comprising: a receiver; a barrel mounted to said receiver and at least partly defining at its rear end a firing chamber loadable with a round of ammunition adapted to discharge gas rearwardly thereof on being fired; bolt means cooperable with the rearward end of said firing chamber and reciprocable in said receiver to extract from said chamber a spent round of ammunition, load thereinto a fresh round and cock said firearm for another firing cycle, said bolt means having a gas passageway extending longitudinally therethrough; yieldable means for urging said bolt means forwardly towards said firing chamber, said bolt means being urged rearwardly of said firing chamber by gas pressure on said bolt means developed in said firing chamber; a reciprocable piston at least partly within said passageway and defining a second passageway extending through said piston in communication with said exhaust tube means and with said passageway during at least a portion of the firing of said firearm; and releasable locking means to lock said bolt in its forward position and releasable by travel of said piston rearwardly a predetermined distance; and gas exhaust tube means associated with said receiver for receiving gas from said passageway and discharging said gas rearwardly of said firearm.
 7. A firearm as defined in claim 6 including sear means associated with said bolt for releasably retaining said piston in a rearward position.
 8. A firearm as defined in claim 7 including cocking means associated with said piston for engaging said bolt after said piston has moved rearward a predetermined distance to move said bolt rearwardly and to cock same.
 9. The firearm of claim 8 wherein said locking means engage said barrel, or an element fixEdly attached thereto, with said bolt by rotation of said bolt, said receiver having a longitudinal axial slot therein, said bolt having a longitudinal and angled locking slot therein, said cocking means attached to said piston and extending through said bolt slot and said receiver slot, whereby reciprocable movement of said piston causes corresponding movement of said cocking means, within said bolt slot and rotation of said bolt to lock and release said bolt by said locking means. 